Nuevos datos sobre las tortugas del Cretácico Inferior de Níger en las X Jornadas Internacionales de Salas de los Infantes

Siguiendo con una de las líneas de investigación que desde hace varios años se desarrollan desde el Grupo de Biología Evolutiva de la UNED, en las recientemente celebradas X Jornadas Internacionales de Salas de los Infantes se presentó una comunicación oral sobre la diversificación de las tortugas pleurodiras en el Cretácico Inferior de Gondwana, a partir de hallazgos realizados en la célebre localidad de Níger de Gadoufaoua. Concretamente, esta investigación se centra en el estudio del hasta ahora mal conocido caparazón de la forma del Aptiense Teneremys lapparenti. El resumen de esta contribución, titulada “Shell anatomy of the pleurodiran turtle Teneremys lapparenti, from the Aptian of Gadoufaoua (Niger)”, es el siguiente:

One of the most relevant fossil localities for understanding the Lower Cretaceous vertebrate record of the African continent is Gadoufaoua. This region is located in the Illumeden Basin, in the central region of Niger (Ténéré Desert, south-central region of the Sahara Desert). The fossil remains come from Aptian levels. Several lineages have been found there, including the identification of several pleurodiran turtles. This represents the oldest documented synchronistic and sympatric presence of several pleurodiran representatives in Africa, as well as one of the oldest globally. The first study of this turtle fauna was published in the early 1980s. Broin (1980) documented the presence of at least three taxa. One of them, attributed to the new turtle Taquetochelys decorata, was recognized as belonging to the extinct lineage Araripemydidae. The other two turtles from Gadoufaoua were identified as belonging to ‘Pelomedusidae (s.l.)’, a term used by her to group the podocnemidids, the pelomedusids, and the bothremydids, but not the araripemydids nor the chelids. One of them was defined as a new species, Teneremys lapparenti, but the other was referred to as Platycheloides cf. nyasae.

Taquetochelys decorata is the only species of Araripemydidae identified in Africa. Both its cranial and postcranial anatomy are well-known, so that it represents one of the best characterized Cretaceous pleurodiran turtles. Almost 40 years after the study of Broin (1980), the shell from Gadoufaoua attributed by her to Platycheloides cf. nyasae, as well as other shells and carapacial remains corresponding to the same species, were detailed studied. They were attributed to a new taxon, Francemys gadoufaouaensis, exclusive to that locality. This turtle was recognized as a representative of Pelomedusoides closely related to Podocnemidoidea, but not attributable to this clade or to any of the families so far defined. 

Teneremys lapparenti was defined by a shell fragment (preserving the partial carapace but a very small area of the plastron) associated with a skull (partially visible only in ventral view). An isolated nuchal plate was tentatively attributed to it. New information relative to the cranial anatomy of Teneremys lapparenti was subsequently provided, but not on its shell. Since Francemys gadoufaouaensis is only known from the shell, new data on this anatomical region in Teneremys lapparenti would be vital for comparing both taxa and, consequently, for better understanding how the successful radiation experienced by the Pelomedusoides in northern Gondwana during the Aptian-Cenomanian interval occurred (see Pérez-García, 2019b). In fact, the scarce shell information currently available on Teneremys lapparenti allows to recognize that it shares several derived characters in relation to other forms of Pelomedusoides with Francemys gadoufaouaensis, to which it may be closely related.

Abundant shell remains from Gadoufaoua compatible with Teneremys lapparenti, including several relatively complete shells, are available for study. This material is presented here. Thanks to the analysis of these fossils, some preliminary conclusions related to the diversity and disparity of Pelomedusoides during the Early Cretaceous, as well as concerning the precise phylogenetic position of the representatives from Gadoufaoua, are proposed. 

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Más información:

Referencia: Pérez-García, A. Shell anatomy of the pleurodiran turtle Teneremys lapparenti from the Aptian of Gadoufaoua (Niger). In P. Huerta, F. Torcida, J.I. Canudo and X. Pereda (eds.). Abstract Book/Libro de resúmenes X Jornadas Internacionales sobre Paleontología de Dinosaurios y su entorno, 181-182.

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